External seizure mechanism for RF node connector

ABSTRACT

A spring-loaded device is installed into a node housing at a predetermined location. The predetermined location is selected to correspond to another predetermined location into which a stinger may be installed. These predetermined locations on the node housing are selected to further correspond to a predetermined internal location of an RF interface connector. A conducting pin of the RF interface extends through a dielectric between a nail head shaped end, which provides electrical connection with the stinger projection, and an end soldered to a PCB of the amplifier. The amplifier may be installed and the node housing closed before the stinger and spring-loaded device are installed into the housing. This facilitates installation of the stinger into the housing without having to open the housing and remove the amplifier. External threads on the spring-loaded device facilitate installation thereof, but a unique torque is not required therefor.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority under 35 U.S.C. 119(e) toPfister, et al., U.S. provisional patent application No. 60/340,403entitled “External Seizure Mechanism For RF Node Connector”, which wasfiled Dec. 14, 2001, and is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] This invention relates, generally, to communicationnetworkshaving radio frequency (“RF”) amplifiers, and, moreparticularly, to connections at network nodes.

BACKGROUND

[0003] As broadband networks continue to move from the experimentalrealm to the order of the day for network and service providers, thecompetition-driven need for providers to reduce costs of implementationincreases proportionally. Community Antenna Television (“CATV”) hastraditionally relied on metallic coaxial (“coax”) cabling to delivervideo signals. The conductors that transport the signals through thenetwork may be typically connected at various points within the network,such as head ends, or central offices, nodes and subscriber premiseequipment (“SPE”) devices. The conductors are typically connected at thevarious types of equipment with connectors that are typically designedto minimize signal loss and to have impedance that matches that of theconductor(s) being connected.

[0004] The nodes may include electrical devices that are locatedoutdoors and may be aerially hung from a conductor strand. Whether anode is mounted inside a cabinet affixed to the ground, or installedaerially, a technician typically installs a stinger, a device known inthe art for providing an RF connection through a penetration into ahousing. The stinger may comprise a hollow metallic shell threaded onthe outside, a center conductor and a dielectric interposed between theconductor and the inner surface of the shell. The center conductorprojects axially from the stinger such that the device resembles a beestinger, hence the name. There are various types and styles of stingersknown in the art, some designed for lab testing and some designed forfield-use. In a lab-test style stinger, the end opposing the projectingconductor typically has a RF terminal. The field-use stinger typicallyhas a mechanism for capturing and transferring electrical signals to theshield and conductor of a coaxial cable. The stinger is threaded intothe node housing penetration, which is typically threaded to receive thestinger. When the stinger is in the installed position, the conductorprojection into the node housing is guided into a predeterminedposition. The stinger conductor is guided by a guide device that mayinclude a narrow channel to locate the conductor such that the nail headof a threaded seizure connector device may contact the center conductorwhen the seizure connector is screwed into place towards the guide, theaxis of the seizure connector being perpendicular to the stingerconductor. Moreover, the seizure connector is typically screwed intoplace with a predetermined torque, the torque value determined to causethe center conductor to be “seized,” or clamped, between the nail headand a metallic button that is located on the surface of the guide deviceunderneath the center conductor.

[0005] To guide an RF signal from the stinger conductor through theseizure connector, the nail head penetrates the seizure connectorthrough a dielectric device and terminates with a conducting pin insidea barrel defined by the seizure connector. This forms the male end of anRF connector such that the center conductor penetrates a matching femaleRF connector affixed to an amplifier assembly that housesnode-processing circuitry. Although this arrangement provides acceptabletransfer of RF signal power into or out of a node, the process ofinstalling a node or performing maintenance is cumbersome because thestinger must be installed before the seizure connector is screwed intoplace using a torque wrench.

[0006] The seizure connector is screwed into place before the amplifieris located within the housing and the connection between the networkconductor and the node circuitry is made. Furthermore, if the torquevalue for installing the seizure connector is exceeded, the stingercenter conductor may be deformed, possibly causing degradation of thetransfer of the RF signal power from the stinger to the seizureconnector. On the other hand, if the torque value is too low, theconnection between the nail head of the seizure connector and thestinger conductor may not be sound, thus resulting in poor signal powertransfer as well. In addition, even if the torque applied in installingthe seizure connector is proper, the nail head surface, as well as thestinger conductor, may nevertheless become deformed. This is because thenail head is turning against the stationary stinger conductor as theforce imparted to the conductor is increasing, thus gouging the contactsurfaces, which may result in decreased transfer of signal power at RFsignal frequencies.

[0007] To replace a stinger or remove a node, especially a node that isaerially hung from a strand, the amplifier, which may be secured intothe node with a plurality of screws or other fasteners known in the art,must be removed. This typically requires opening the node housing, whichmay typically be a hinged, clamshell housing fastened with screws orother known fasteners. After the amplifier has been removed from thehousing, the seizure connector is unscrewed so that the seizing, orclamping force, exerted by the seizure connector nail head towardsstinger conductor and opposed by the guide button, is relieved so thatthe stinger can be unscrewed from the node housing.

[0008] Thus, there is a need for a method and system that reduces thenumber of steps for installing or removing a stinger from a node, thusresulting in a less cumbersome method of installing a node in a network.Furthermore, there is a need for a method and system for providing aneven and constant exertion of force for maintaining contact between thestinger conductor and the nail head. There is also a need for a methodand system for minimizing damage that may occur to the stinger conductorand nail head contact surface areas due to gouging as the seizureconnector is screwed towards the stinger conductor.

SUMMARY

[0009] An objective of the invention is to provide a simplified methodand system for seizing a stinger center conductor between a forceexerting means and the end of a conducting pin, the pin being part of aconnector means having an axis perpendicular to the axis of the centerconductor, to facilitate transferring of electrical energy from thestinger to the connector.

[0010] It is another objective to provide a means of exerting said forsuch that a unique torque is not specified for providing contact betweenthe stinger conductor and the pin. Furthermore, it is an object toprovide a method and system for exerting said force in a substantiallyconstant amount regardless of slight tolerance variations in thealignment among the stinger center conductor, the force exerting meansand the pin of the connector.

[0011] It is yet another object to provide a method and system forexerting a force on the stinger conductor, thereby bringing it intocontact with the center pin of the connector, but without gouging thesurfaces of contact of the pin or the stinger conductor.

[0012] Generally described is a system for connecting an RF node into anetwork comprising means for electrically interfacing with a stingersignal conductor and means for exerting a resilient force opposing theinterfacing means, the exerted force maintaining the stinger conductorin positive contact with the interface means. The exerting means mayinclude a non-conductive plunger having a distal face for applying theexerted force towards the electrical interface means. A transitionbetween the distal face and a side face of the plunger may be chamfered.The interface means may include a conductor button, also referred to asa nail head, for contacting the stinger conductor at a contact area, thebutton being at the end of a pin that functions as the center conductorthrough a dielectric.

[0013] The exerting means may be rigidly installed into a housing, thehousing defining mounting holes for the exerting means and the stingersuch that an axis of the exerting means and the interface means arecoaxial. The interface means may be rigidly mounted and located to acircuit amplifier such that when the amplifier is installed into thehousing, the stinger conductor may be interposed between the exertingmeans and the electrical interface means at a right angle to the axis ofthe opposing interface and exerting means when the stinger is installedinto the housing.

[0014] Also generally described is a method for installing a nodecomprising the steps of rigidly attaching at a predetermined location ona circuit board of an amplifier an RF connector having an electricalinterface, installing a stinger into a housing of the node andinstalling a force exerting means for resiliently forcing the centerconductor of the stinger against the electrical interface of the RFconnector. The amplifier may also be installed into the node housingbefore or after the exerting means has been installed.

[0015] A process to remove the node comprises the steps of partiallyremoving the exerting means from the housing to reduce or remove theforce exerted against the stinger conductor and removing the stingerfrom the housing. The amplifier may also be removed from the nodehousing if the exerting means has not been removed.

BRIEF DESCRIPTION OF DRAWINGS

[0016]FIG. 1 illustrates a typical outdoor strand mounting of a node.

[0017]FIG. 2 illustrates a typical node housing with modules installed.Two stingers are shown, one installed and the other before installation.FIG. 3 illustrates an electrical interface aspect that penetrates anamplifier chassis and is attached to a printed circuit board.

[0018]FIG. 4 illustrates a plunger aspect for forcing a stingerconductor into contact with an electrical interface aspect.

[0019]FIG. 5 illustrates an installation of as electrical interface anda plunger, the plunger partially installed, into a node housing beforeelectrical contact between the electrical interface and a stinger centerconductor is made.

[0020]FIG. 6 illustrates an installation of as electrical interface anda plunger into a node housing such that electrical contact between theelectrical interface and a stinger center conductor is made.

DETAILED DESCRIPTION

[0021] As a preliminary matter, it readily will be understood by thosepersons skilled in the art that the present invention is susceptible ofbroad utility and application. Many methods, embodiments and adaptationsof the present invention other than those herein described, as well asmany variations, modifications, and equivalent arrangements, will beapparent from or reasonably suggested by the present invention and thefollowing description thereof, without departing from the substance orscope of the present invention.

[0022] Accordingly, while the present invention has been describedherein in detail in relation to preferred embodiments, it is to beunderstood that this disclosure is only illustrative and exemplary ofthe present invention and is made merely for the purposes of providing afull and enabling disclosure of the invention. The following disclosureis not intended nor is to be construed to limit the present invention orotherwise to exclude any such other embodiments, adaptations,variations, modifications and equivalent arrangements, the presentinvention being limited only by the claims appended hereto and theequivalents thereof. Furthermore, while some aspects of the presentinvention are described in detail herein, no specific metallic, plasticor other material, housing or chassis shape, or connector size, forexample, is required to be used in the practicing of the presentinvention.

[0023] Turning now to the figures, FIG. 1 illustrates a typicalarchitectural scenario 2 of a broadband network where a network node 4is stand-mounted from a support wire 6. Cables 10, 11, 12 and 13 maytypically be coaxial cables for transmitting RF signal information aswell as AC power. Information signals may be provided to and transmittedfrom node 4 via multiple optical fiber inputs in line bundle 8 andreturned to the network via output lines 10, 11, 12, and 13. Node 4typically provides information signals to subscribers via subscriberdrop line. Coaxial cables may each be connected to a connector means atthe outside of the housing of node 4, the connector means typicallypassing the signal through a penetration in the outer wall of thehousing. The connector means that passes are typically designed toprovide a watertight seal, since node 4 is exposed to the elements, asopposed to merely passing a cable through a hole in the side of thehousing and directly connecting the cable to a circuit board inside.

[0024] Turning now to FIG. 2, a node housing 14 is shown in an openstate. As shown in the drawing, housing 14 may typically be a hingedclamshell enclosing various components, such as modules 15 A-n, in thelower portion, or lid 16 of the housing. The upper portion 18, or base,of node housing 14 may typically contain an amplifier chassis 19 shownin the drawing as a chassis outline for clarity, the chassis typicallybeing a rigid frame like structure for mounting a printed circuit board(“PCB”). The term “amplifier” and function thereof are known in the artand the PCB circuitry typically includes means for providing RF signalinterface functionality. For example, this functionality may includeseparating or isolating a low frequency power supply signal from a highfrequency RF signal, before the separated or isolated signals arefurther processed and then provided to or received from modules 15 andother circuitry contained in lid 16. It will be appreciated that onlythe outline of amplifier 19 is shown, although the edges hidden by base18 are shown as dashed lines. Otherwise, as amplifier 19 would obscuretheir view, some items to be described hereafter in connection with FIG.2 would have to be shown with dashed lines, thereby reducing clarity.Similarly, the PCB is not shown in the drawing for clarity so as not toobscure the view of items to be discussed hereafter. However, amplifier19 as used in the illustrated embodiment may be thought of as arectangular baking dish oriented so that the viewer of the figure islooking into the dish with the PCB being inside the dish, the bottom ofthe “amplifier” being oriented into the drawing when placed within base18.

[0025] As discussed above, a watertight connection is provided to passthe RF and power signal from a coaxial line through node base 18. Thesignal typically penetrates base 18 via a stinger 20, stingers beingknown in the art. Stinger 20 may be threaded so that matching threads inport 22 receive the stinger, which may also locate a sealing O-ring orgasket between nut 24 and port 22. Stinger 10 typically has a captureand locking mechanism at network side 26 for transferring electricalsignals to connecting lines, such as lines 10, 11, 12, and 13 shown inFIG. 1. The housing side of stinger 20 typically includes a centerconductor 28 that transfers a non-grounded signal received at networkside 26 to the inside of housing 14. The stinger conductor 28 istypically forced into contact with another connecting means insidehousing 14, the other connecting means having an axis substantiallyperpendicular to the axis of stinger 20, which runs coaxially withcenter conductor 28. The other connecting means is typically part of asystem of two assemblies, which will be described infra, the systembeing referred to as a seizure mechanism.

[0026] One of the assemblies, a force exerting means 30A-n, typically isinstalled into the into ports 32A-n of base 18. The force from exertingassembly 30 is opposed by an RF electrical interface means 34, which istypically mounted rigidly to a PCB that is located by amplifier chassis19. Amplifier chassis 19 locates interface means 34 such that thecoaxial axis of the interface means and exerting means 30 issubstantially perpendicular to the axis of stinger 20, such thatconductor 28 intersects said coaxial axis. It will be appreciated thatthere will typically be a like number of interface means 34 as there areexerting means 30 and stingers 20. However, only one interface means 34is shown in FIG. 2 for clarity. Furthermore, all ports 22 and 32, andhence stingers 20 and exerting means 30 respectively, need not belocated at one end of housing 16, as those skilled in the art candetermine the best location of these items, based on particularinstallation needs. It will further be appreciated that housing 16 maybe manufactured with a plurality of ports 22 and 32, in number greaterthan the number actually used, in which case the unused ports could besealed with a blind plug known in the art, such as a port plug, forexample.

[0027] Turning now to FIG. 3, the electrical interface means 34 of theconnector system is illustrated in detail. The interface assembly 34 isattached to PCB 36, which is mounted to amplifier chassis 19. The bodyof interface 34 may typically be made out of a conducting material, suchas brass, for example, and may comprise a castellated ring section 38,the castellations 40 defining PCB mounting prongs 42 projecting fromsaid castellations. It will be appreciated that although twocastellations 40 and prongs 42 are shown, the number of castellationsand prongs may be more or less than two.

[0028] The body of interface 34 further includes barrel 44, whichextends from ring section 38. Barrel 44 extends from ring 38 to theextent that it passes through and beyond amplifier chassis 19.Furthermore, barrel 44 may typically be threaded around the outside toreceive retaining nut 46. Thus, barrel 44 extends beyond outer face 48of amplifier chassis 19 to provide enough threads for securing interface34 and chassis 19 with nut 46. It is noted that the cross section ofring section 38, as well as nut 46 will typically be larger that thehole in chassis 19 through which barrel 44 passes. Thus, interfaceassembly 34 may be rigidly attached to chassis 19 for mechanicalstability, and, in addition, to provide system ground interconnectionfrom the chassis to the interface assembly. This also bolsters theground interconnection between chassis 19 and PCB 36 if prongs 42 areattached to ground traces, such as with solder, for example.

[0029] To provide RF signal transfer, dielectric 50 is forcefullyretained within barrel 44 and extends through and past the projectedextent of the barrel. Within dielectric 50, conducting pin 52 isforcefully retained, and may be soldered to PCB 36 at solder ball 54.Conducting pin 52 extends past the dielectric projection approximately0.125″, for example, whereupon the pin flares slightly to create a nailhead surface 56 that provides a contact surface for the stinger centerconductor, as described above.

[0030] Turning now to FIG. 4, exerting means 30 is shown in thepreferred embodiment as a plunger arrangement. The body of exertingmeans 30 includes barrel 58, plunger 60 and spring 62. Spring 62 iscompressed within barrel 58 such that plunger 60 is motivated away fromflange 64 and hexagonal head 66. Plunger 60 is restrained from beingexpelled from the barrel as plunger base 68 is forced into contact withstop lip 70. Barrel 58 is threaded so that after a stinger has beeninstalled into a node housing, a technician may install the exertingmeans 30 into the node housing by turning hexagonal head 66 with awrench. Application to exerting device 30 of a unique and specificallynarrow unique torque value, or range of values, is not required wheninstalling it to ensure that the force exerted against a stingerconductor is within a narrow range. This is because plunger 60 is springloaded with spring 62, which is preferably a coil or other type ofspring having a typically linear force versus displacement curve.

[0031] Thus, manufacturing tolerance of the distance between flange 64and plunger end 72 need not be extremely precise to ensure that apredictable force is applied to the stinger conductor. If spring 62 ismanufactured to have sufficient deflection (preferably on the order ofapproximately four or five times the diameter of the stinger centerconductor, but can be more or less, depending upon criteria determinedby one skilled in the art), a field technician may turn hexagonal head66, which is rigidly connected to barrel 58, until flange 64 is stoppedagainst the outside of the node housing. An additional quarter turn forexample, may be applied to hexagonal head 66 to ensure that it isadequately seated against the housing. Thus, installation is quick andeasy, without the requirement of using a torque wrench, or other specialtools. The nominal excess deflection designed into the compressionlength of spring 62 compensates for differences in length betweenplunger end 72 and flange 64, as well as other slight manufacturingdifferences, such as, for example, the distance between the housing faceagainst which flange 64 stops and the centerline of the penetration intowhich a stinger is installed.

[0032] Along with the even exertion of force provided by the springloaded characteristic of plunger 60, chamfering of plunger end 72 mayfurther facilitate installation of a stinger into a node for a newinstallation, or even an existing node upon which coaxial linemaintenance is being performed. To reinstall the stinger, the plunger 60will typically be loosened a few turns to provide clearance betweenplunger end 72 and the nail head.

[0033] Turning now to FIG. 5, housing base 18 is shown with amplifierassembly 19 and stinger 20 installed. Amplifier chassis 19 is shown withsupport legs dashed for clarity, although the legs would be as visibleas the rest of the chassis as shown in the figure. Exerting device 30 isshown partially installed; it will be appreciated that as hexagonal head66 is turned clockwise (for right hand threads), the exerting devicewill move closer and closer to interface 34 until plunger end 72contacts stinger conductor 28. This contact forces stinger conductor 28into contact with nail head 56 to result in electrical connectionbetween RF path 74 of stinger 20 and solder ball 54 on PCB 54. Afterplunger 72 contacts conductor 28 and pushes it against nail head 56,turning of hexagonal head 66 may continue without damage occurring tothe stinger center conductor, because spring 62 compresses as flange 64moves closer to housing 16. If spring 62 is a properly designed coilspring, for example, its characteristics should obey Hooke's Law, whichis F=k*x. F is the force exerted by a linear spring, x is the amount ofdistance a spring has deflected from its rest state and k is known asthe spring constant. If exerting device 30 is manufactured such thatspring 62 is in a partially compressed state, a force in accordance withHooke's Law will be exerted against plunger base 68 and flange 64, whichis rigidly attached to barrel 58. This force may be referred to as thepreload (P) of spring 62. Thus, the as-installed force equationrepresenting the force exerted by plunger 72 when it forces conductor 28into contact with nailhead 56 is F=P+k*x.

[0034] If device 30 is manufactured such that k is low and preload P isless than the force that could cause damage to either conductor 28 orinterface 34, then the force applied by plunger 72 will be essentiallythe preload force P regardless of how many turns of as hexagonal head 66are used to bring flange stop 64 into contact with the node housing, thefinal position of the plunger for forcing the conductor into contactwith nailhead 56. Those skilled in the art will appreciate that althoughthe force will increase proportionally with deflection of spring 62(caused by continued turning of hexagonal head 66 after plunger 72 hasmotivated conductor 28 into contact with nail head 56), if the springconstant k is kept low, the increase will be slight. Accordingly, forall practical purposes, the changes in force pushing conductor 28against nail head 56 will be negligible as hexagonal head 66 is turnedafter plunger 72 contacts conductor 28 and conductor 28 subsequentlycontacts nail head 56.

[0035] Turning now to FIG. 6, housing base 18 is shown with amplifierassembly 19 and stinger 20 installed. Exerting device 30 is shown fullyinstalled with plunger 72 exerting force against conductor 28, theexerted force pushing conductor 28 against nail head 56. It is notedthat hexagonal head 66 has been turned until flange 64 seated againstport 32. It is also noted that plunger 72 extends a smaller distancebeyond the top of device 30, and that plunger 68 (shown in dashed linesbehind the threads of barrel 58) is recessed into the barrel, ascompared to the same items as shown in FIG. 5. It is further noted thatthe coils of spring 62 are closer together, indicating that the springhas deflected to accommodate the seating of flange 64 against port 32.As discussed above, if spring 62 has a properly designed spring factork, the force exerted by plunger 72 against conductor 28 will fall withina range between zero, when the plunger first contacts the conductor, andpossibly up to a value slightly higher than preload P. Thus, regardlessof manufacturing tolerances of the dimensional relationship between thecenterline of port 22 and the plane of housing 18 in which port 32 lies,or the dimensional relationship of nail head 56 thereto, stinger 20 maybe installed and reliably connected to the nail head by screwingexertion device 30 into port 32 until flange 64 bottoms thereon.Therefore, a field technician need not have to remove amplifier chassis19 in order to install stinger 20 into housing 16, nor have to apply apredetermined torque to device 30 to ensure positive electrical contactbetween conductor 28 and nail head 56 while preventing damage from overtightening. Accordingly, time needed for a technician to install ormaintain a node is reduced. The spring may also be designed not to exerttoo much force that would damage the stinger in the case that theamplifier is removed for maintenance while the plunger is stillinstalled from the initial installation. This design provides anadditional benefit to the technician when servicing the amplifier. Theamplifier may be removed and replaced without removing the stinger fromthe housing.

[0036] These and many other objects and advantages will be readilyapparent to one skilled in the art from the foregoing specification whenread in conjunction with the appended drawings. It is to be understoodthat the embodiments herein illustrated are examples only, and that thescope of the invention is to be defined solely by the claims whenaccorded a full range of equivalents.

What is claimed is:
 1. A system for connecting an RF node to a network:means for electrically interfacing with a center conductor of a stinger;and means for exerting a resilient force opposing the interfacing means,the exerted force maintaining the stinger conductor in contact with theinterface means.
 2. The system of claim 1 wherein the exerting meansincludes a non-conductive plunger having a distal face for applying theexerted force towards the electrical interface means.
 3. The system ofclaim 2 wherein a transition between the distal face and a side face ofthe plunger is chamfered.
 4. The system of claim 1 wherein the interfacemeans includes a conductor nail head for contacting the stingerconductor at a contact area.
 5. The system of claim 1 wherein theelectrical interface means and the exerting means are rigidly mountedinto a housing, the housing defining mounting holes for the interfacemeans, the exerting means and the stinger such that the axes of theexerting means and the interface means are coaxial, the stingerconductor interposed between the exerting means and the electricalinterface means.
 6. A device for exerting a force within a node housingcomprising: means for producing a force; means for containing the forceproducing means; extensible means for translating force produced by theforce-producing means outward from the containing means; means forpreventing expulsion of the translating means from the containing meansdue to force from the force-producing means; and means for securing thedevice to the housing such that the translating means provides force ina predetermined direction at a predetermined location within thehousing.
 7. The device of claim 6 wherein the force producing meansincludes a spring.
 8. The device of claim 7 wherein the spring ishelical.
 9. The device of claim 6 wherein the containing means is abarrel.
 10. The device of claim 6 wherein the securing means includethreads on the outside of the containing means.
 11. The device of claim6 wherein the translating means includes a plunger and a base coaxiallyrelated, the base extending perpendicularly from the axis a greaterdistance than does the plunger, the expulsion-prevention means includinga stop lip defining an opening larger than the perpendicular extent ofthe plunger but smaller than the perpendicular extent of the base.
 12. Amethod for electrically connecting a stinger into a network nodecomprising: locating an RF interface device on a printed circuit boardsuch that the interface device extends through an amplifier chassis at apredetermined location, the interface device having a nail head formaking electrical contact with a center conductor of a stinger at theextent of the interface device; installing the amplifier within a nodehousing such that the nail head is located at a predetermined locationwithin the housing; installing the stinger into a predetermined openingin the housing such that the center conductor is proximate the nailhead; and installing into the housing at a predetermined location aforce exerting device such that the center conductor is forcibly broughtinto electrical contact with the nail head.
 13. The method of claim 12further comprising the step of closing the node housing beforeinstalling the stinger.